Biology, Chemistry and Physics are the big 3 for high school for a college-prep track. If he plans on going into a STEM field, a 4th year of science is highly recommended.
Apologia is a Christian curriculum that is generally well-regarded for science, but there are many others. My DD was in public school for most of 9th, and finished that year with their curriculum.
For 10th grade, she took Apologia Chemistry with Lab in a class taught by another homeschool mom.
This year, she's taking her elective in Astronomy at the local community college.
Next year, she'll take Honors Physics back at the high school.
August 23 at 9:40 PM
My kid is taking chemistry this year for 10th.
Usually in the public schools, at least around here, it's biology first. However, this is mostly because many 10th graders haven't had the math necessary to handle chemistry or physics. My son is in 9th this year, and we actually decided to have him do chemistry since he's had the necessary math (and I'm actually somewhat sympathetic to the view that it's really physics that's the base science, then chemistry, then bio -- and then the more specialized anatomy, botany, etc.). It's really up to you, though, as long as he can achieve the necessary proficiency in either one.